TUFLOW Message 2831

TUFLOW Message
ERROR 2831 - More than 1 parent polygon for polygon with nesting level "<>".

Alternate Message
NA

Message Type
ERROR

Description
This error is triggered if a nesting level polygon sits completely within more than one parent polygon. A parent polygon is any nesting level polygon that completely encompasses a given polygon and has a lower nesting value. It is also only considered a direct parent if it has the closest nesting level value to the child polygon of all polygons that encompass it. Example, a polygon with nesting level 4 can sit completely within a nesting level 3 polygon and completely within a nesting level 2 polygon. It can also sit completely within a nesting level 2 polygon (skipping level 3), but it cannot sit completely within two level 3 polygons or within two level 2 polygons.

Suggestions
Double check the 2d_qnl layers to ensure that each polygon only has a single direct parent. Open the messages_P.shp to view which nesting level polygon is causing the issue. Quite often, intermediate polygons are not required as TUFLOW will automatically transition between nesting levels. E.g., it is common that nesting levels are drawn without any parents, and TUFLOW will assume the domain extent to be the level 1 nesting polygon and create transition mesh elements accordingly.

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